Flame-retardant composition

ABSTRACT

A normally flammable organic polymer is rendered flame retardant by the incorporation of a compound corresponding to the formula:   WHEREIN X is chloro or bromo, Q is halo, hydrogen, or a hydrocarbyl or hydrocarbyloxy group, and Z is a divalent saturated polybromocycloalkylene group containing 5-16 carbon atoms and 2-6 bromine atoms. Such flame retardants include, e.g., 5,6-dibromo-1,10,11,12,13,13hexachlorotricyclo(8.2.1.02,9)tridecene-11, i.e., the dibrominated 1:1 Diels-Alder adduct of hexachlorocyclopentadiene and cyclooctadiene-1,5. If desired, the flame retardant may be employed in conjunction with a synergist, such as antimony trioxide.

United Stat Newcombe l FLAME-RETARDANT COMPOSITION [75] Inventor: JackNewcombe, Freehold, NJ.

[73] Assignee: Cities Service Company, Tulsa,

Okla.

22 Filed: Oct. 3, 1973 21 Appl. No.: 402,960

Related U.S. Application Data [60] Division of Ser. No. 281,692, Aug.18, 1972, which is a continuation-in-part of Serv No. 115,081, Feb. 12,1971, abandoned.

[52] U.S. C1 260/45.7 R; 106/15 FP; 117/137;

260/4575 B [51] Int. Cl. C08f 45/58; C08g 51/58 [58] Field of Search260/4575 B, 45.7 R

[56] References Cited UNITED STATES PATENTS 8/1962 Schmerling 260/6481/1968 Norell 260/4575 3,396,201 8/1968 Weil et a]. 3,403,036 9/1968Hindersinn et a1. 260/4575 3,697,607 10/1972 Cardenas 260/457 PrimaryExaminerV. P. Hoke Attorney, Agent, or FirmPatricia .l. Hogan [451 Aug.12, 1975 l 5 7 ABSTRACT A normally flammable organic polymer is renderedflame retardant by the incorporation of a compound corresponding to theformula:

1 Claim, No Drawings FLAME-RETARDANT COMPOSITION CROSS-REFERENCE TORELATED APPLICATION This is division, of application Ser. No. 281,692,filed Aug. 18, 1972, which in turn is a continuation-in-part ofapplication Ser. No. 115,081, filed Feb. 12, 1971, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to flame-retardant compositions and more particularly relates tosuch composi tions comprising normally flammable organic polymers andnovel halogenated organic flame retardants.

2. Description of the Prior Art It is known that halogenated compoundsare sometimes useful for imparting flame retardancy to normally Iflammable organic polymers. However, the halogenated compounds whichhave been proposed for use as flame retardants usually have one or moreof the following disadvantages: volatility, instability at processingtemperatures, incompatibility, inefficiency, and toxicity.

1f the halogenated compound is too volatile, it does not remain in thepolymer to function as a flame retardant when needed. If it is unstableat processing temperatures, it decomposes to cause corrosion of theequipment and discoloration of the polymer. If it is incompatible withthe polymer, it exudes to the surface to form an esthetically unpleasingdeposit, the removal of which results in removing the flame retardancywhich the compound was supposed to impart. If it is inefficient, it mustbe used in such high concentrations that it has an unduly deleteriouseffect on polymer properties and unduly increases the cost of thefabri-. cated polymer. If it is toxic, it presents more-or-less serioushazards to the health and/or life of fabricators and users of theflame-retardant composition in which it is used and also presents anecological problem when the fabricated polymer is discarded.

Since some of these disadvantages make a compound less than desirablefor use as a flame retardant, and others actually prevent it from havingany practical utility as a flame retardant, it is apparent that there isa need for a flame retardant which is substantially nonvolatile, stableat processing temperatures, compatible, efficient, and non-toxic. 4

It is believed that the general lack of success of the prior art inproducing such a flame retardant is at least partially due to thetendency of a given factor to degrade at least one of these propertieswhile improving another. For instance, it has been found that compoundscontaining cycloaliphatic bromine are sometimes more efficient thanother halogenated compounds, but these compounds have poor stability atprocessing temperatures and frequently have other disadvantages, such asvolatility, incompatibility, and toxicity. Compounds containing vinylicbromine on the ring carbon atoms are more stable but less efficient, andthey may also be too volatile, toxic. and incompatiblc.

It might be thought that the toxicity of halogenated compounds could bereduced by decreasing their halogen contents, but this has not beenfound to be the case. Comparison of halogenated insecticides havingsimilar structures indicates that toxicity does not simply increase withan increase in halogen content and, in

. percent and an LD5 number of 570.

SUMMARY OF HE INVENTION An object of this invention is to provide novelflameretardant organic polymer compositions.

Another object is to provide such compositions containing a flameretardant which has practical utility.

A further object is to provide such compositions wherein the flameretardant is substantially nonvolatile, stable at processingtemperatures, compatible,

efficient, and non-toxic.

These and other objects are attained by intimately mixing a normallyflammable organic polymer with a flame retardant corresponding to theformula:

wherein X is chloro or bromo, Q is halo, hydrogen, or a hydrocarbyl orhydrocarbyloxy group, and Z is a divalent saturatedpolybromocycloalkylene group containing 5-16 carbon atoms and 2-6bromine atoms; said valences being on adjacent carbon atoms.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The normally flammable organicpolymer which is rendered flame retardant in accordance with theinvention may be natural or synthetic but is preferably a solidsynthetic polymer, more preferably a polymer of an unsaturatedhydrocarbon. Exemplary of the polymers are cotton, wool, silk, paper,natural rubber, wood, paint, the high molecular weight homopolymers andcopolymers of unsaturated aliphatic and aromatic hydrocarbons (e.g.,ethylene, propylene, styrene, etc.), acrylic polymers (e.g.,polyacrylonitrile, polymethyl methacrylate, etc.), alkyd resins,cellulose derivatives (e.g., cellulose acetate, methyl cellulose, etc.),epoxy resins, furan resins, isocyanate resins (e.g., polyurethanes),melamine resins, vinyl resins (e.g., polyvinyl acetate, polyvinylchloride, etc.), resorcinol resins, synthetic rubbers (e.g.,polyisoprene, polybutadiene, butadieneacrylonitrile copolymers,butadiene-styrene copolymers, butyl rubber, neoprene rubber, etc.), ABSresins, and mixtures thereof.

The flame retardant of the invention may be any compound correspondingto the above formula. Such compounds are already known and may beprepared by reacting a polyhalocyclopentadiene with a suitablemulti-unsaturated cycloaliphatic hydrocarbon to form a 1:1 Diels-Alderadduct, and then adding bromine to the residual unsaturation. Ifdesired, additional bromine may be introduced by substitutionbromination.

Alternatively, the bromine may be introduced by starting with anunsaturated cycloaliphatic bromide. It is important that thepolybromocycloalkylene group in the flame retardant be saturated,because the presence of residual unsaturation would decrease theefficiency of the compound as a flame retardant.

Polyhalocyclopentadienes suitable for use in preparing the flameretardants of the invention include hexachlorocyclopentadiene,hexabromocyclopentadiene, 5 ,5 -dimethoxytetrachlorocyclopentadiene, 5,5- diethoxytetrachlorocyclopentadiene,5,5-dihydrotetrachlorocyclopentadiene, 5,S-difluorotetrachlorocyclopentadiene,5,5-dibromotetrachlorocyclopentadiene, etc. The polyhalocyclopentadienescontaining at least two chlorine atoms are preferred, because the flameretardants prepared therefrom appear to have improved dispersibility inmany organic polymers.

Multi-unsaturated cycloaliphatic hydrocarbons suitable for use inpreparing the flame retardants of the invention include cyclopentadiene,bicycloheptadiene, 4-vinylcyclohexene, divinylcyclohexane,cyclooctadiene-l,3, cyclooctadiene-l,5, dicyclopentadiene,cyclodecadiene-l,5, trivinylcyclohexane, cycloheptatriene-l ,3 ,6,cyclododecatrienel ,5,9, trimethylcyclododecatrienel ,5 ,9, bis(cyclohexenyl)ethylene, cy-- clooctatetraene, cyclohexadecatetraene-l,5,9,] 3, etc.

The preferred flame retardants of the invention are those wherein X andQ of the formula are chloro, the bromine atoms of thepolybromocycloalkylene group are paired in vicinal positions, thepolybromocycloalkylene group contains 2-4 (most preferably two) bromineatoms, at least some (most preferably all) of the bromine atoms of thepolybromocycloalkylene group are substituents on cycloaliphatic carbonatoms, and/or the polybromocycloalkylene group is monocyclic andcontains 8-l2 carbon atoms in the ring. A particularly preferred flameretardant is 5,6-dibromo- 1,10,] l, l 2, l 3,1 3hexachlorotricyclo[ 8.2.l .0 tridecene-l 1, Le, the dibrominated l:l Diels-Alder adduct ofhexachlorocyclopentadiene and cyclooctadi- The organic polymer isintimately mixed with the flame retardant and any optional additives,such as fillers, pigments, plasticizers, stabilizers, synergists, etc.,in any suitable manner (e.g., by the use of an extruder, a two-rollmill, or a Banbury mixer) to provide a composition containing about 1-25percent, preferably about 4-20 percent, by weight of flame retardant,based on the combined weights of organic polymer and flame retardant.

Although the flame retardants of the invention are fairly efficient, itis frequently desirable to enhance their effectiveness by including oneor more of the compounds of antimony, arsenic, or bismuth, which arewell known synergists for halogenated flame retardants. Antimonytrioxide is particularly useful in this regard. When such a synergist isemployed, it is usually used in an amount such as to provide a flameretardant/synergist weight ratio of about 14.5/ 1, preferably about 2/1.

The flame retardants of the invention are particularly advantageous inthat they are colorless, odorless, relatively insensitive toenvironmental conditions, nontoxic, substantially non-volatile,compatible with polymers, surprisingly stable at processingtemperatures, and efficient. The fact that they are effective at lowconcentrations makes it possible for them to be used to prepareflame-retardant polymer compositions which retain the desirable physicalproperties of the pure polymer to a remarkable extent, and itfacilitates polymer coloring and permits the preparation of flameretardant concentrates.

The following examples are given to illustrate the invention and are notintended as a limitation thereof. Unless otherwise specified, quantitiesmentioned are quantities by weight. The oxygen indices of the basepolymers used in the examples are: polypropylene l8.0, polyethylene17.9, ABS 19.5. The flame retardants ene-l ,5, which has the followingstructural formula: used in the examples and their melting points are:

Designi i IBIIHHLL" M.l. (Il ('l m (Zuni rol (j] til no l l' (1 1 glow(Ion; m1 1: -11..

l1! l" r l L Designation Formula M. P. (C.)

lib-157 Z-lZ-ZH.

EXAMPLE 1 CONTROL Blend polypropylene with an amount of a 2:l mixture ofControl A and antimony trioxide sufficient to form a composition havingan oxygen index of 26.5. Forty parts of the mixture are required.

EXAMPLE ll Repeat Example I except for substituting FR-l for Control A.Only 7.5 parts of the mixture are required, and tests show that theflame-retardant polymer retains the desirable physical properties of thebase polymer to an extraordinary extent.

EXAMPLE Ill CONTROL EXAMPLE lV Repeat Example lll except forsubstituting FR-l for Control B. The test specimens have an oxygen indexof 26.5 and a translucent-white appearance. This shows that the flameretardant is both stable at processing temperatures and compatible withpolypropylene.

EXAMPLE V Blend polypropylene with an amount of FR-l such as to providea bromine cohtent of about 1.3 percent in the blend. The blend has anoxygen index of 21.0.

EXAMPLE VI Prepare six compositions by repeating Example V except foralso blending with various amounts of antimony trioxide. The ratios ofFR-l to antimony trioxide in the blends and the resultant oxygen indicesare shown in Table I.

TABLE I FR-1/Sb O Oxygen Index EXAMPLE v11 Prepare six compositions byblending polypropylene with various amounts of a 2:l mixture of FR-l andantimony trioxide. Mold test specimens from the blends and test foroxygen index. The amounts of flame retardant mixture employed and theresultant oxygen indices are shown in Table II.

TABLE ll FR Mixture Oxygen Index EXAMPLE Vlll gen indices obtained bytests on injection molded samples are shown in Table III.

TABLE III Flame Retardant Oxygen Index EXAMPLE IX Blend low densitypolyethylene with an amount of a 2:1 mixture of FR-l and antimonytrioxide such as to provide a bromine content of about 2.2 percent inthe blend. The oxygen index is 24.5.

EXAMPLE X Blend 15 parts of a 2:1 mixture of FR-l and antimony trioxidewith 85 parts of an impact polystyrene which has been prepared by themass polymerization of styrene in the presence of polybutadiene andwhich has a rubber content of about 5 percent. Test specimens of theblend have an oxygen index of 25.9.

EXAMPLE XI Repeat Example X except for replacing the impact polystyrenewith an ABS resin which has been prepared by the emulsion polymerizationof a :30 mixture of styrene and acrylonitrile in the presence of apolybutadiene rubber and which has a rubber content of about 20 percent.The oxygen index is 30.5.

It is obvious that many variations may be made in the products andprocesses set forth above without departing from the spirit and scope ofthis invention.

What is claimed is:

l. A composition comprising a normally flammable organic polymer and aflame retardant corresponding to the formula:

Cl Br said flame retardant being present in an amount of from 1 to 25percent based upon the combined weights of the organic polymer and flameretardant.

' P0405) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION L Patent3899463 Dated August 12, 1975 Inventor(s) Jack Newcombe It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

. FColumn 4, lines 1-7, the illegible formula should read Cl Br Cl BrColumn 4, lines 46-70, should read Designation Formula M.P. ("C.)

Control A C1 G1 I 0 105-112 Br Br Control B Br Br Page 1 of 3' L J 273 3UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3899463Dated gust 12-, 1975 InventQr(s) Jack Newcombe It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Cl -Br Cl Br Br FR-Z Cl Column 5, lines l-43, should read Cl Br FR-3 Cl-Br 134-142 Cl Br FR-4 Cl Br 154-157 Cl Br L Page 2 of 3 I 37 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3899463 DatedAugust 1975 Inventor(s) Jack Newcombe g 3 It is certified that errorappears in the aboveidentified patent and that said Letters Patent arehereby corrected as shown below:

. F Br I Br FR-5 c1 98-140 C1 C1 O Br Cl Br 242-246 Cl Br Cl Br Br IFR-7 Cl CC Br 127-129 I I Cl H H Br FR-8 C1 CHBrCH Br C1 Signed andSealed this twenty-ezght D ay Of October 1975 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofParentsand Trademarks

1. A COMPOSITION COMPRISING A NORMALLY FLAMMABLE ORGANIC POLYMER AND AFLAME RETARDANT CORRESPONDING TO THE FORMULA: